Cost of writing up your web catalogue $A495, exclusive of the domain registration and hosting costs set out below.

Registration of ".com.au" domain name: currently $A45p/a.

I have found that .com registration, while cheaper, attracts mostly U.S. and other overseas viewers.
Cost of hosting with a local service provider: currently $A77p/a.

I tried quite a few service providers over the years and have found a local one to be the best by far.

Six months as part of the above cost, and thereafter a new contract would need to be negotiated.

With some small businesses, just an occasional update will do. A one-off update of all pages costing $80.

WEBSITE MAINTENANCE

Occasional or regular updates on your website will need to be carried out in order to keep your website performing well in the search engine results pages.
Even if your service or product does not change, sooner or later something on the website will need to be changed, and such changes can be done at very short notice, unlike with print advertising.

I will maintain your website for six months after the initial build or optimisation as part of the package, and thereafter a new agreement will need to be negotiated. Inevitably there is some tweaking to do on the site; it simply is not possible to set up a website perfectly on the first build. After your site is up, either you or I will see things that need to be added or changed.

A new website may well take quite a few months to come up well in the search engine results in any case.  If you have the budget, paid placement on search engines is worth looking at for a brand new website.  Established websites more that a year old probably would be well listed, and should take off with a good makeover and search engine optimisation.